In the past, electronic devices capable of performing a wide variety of functions were quite large. The size of such devices was primarily dictated by the size of the circuitry needed to perform the functions of the device. When vacuum tubes made up the bulk of the electronic circuitry that performed these functions, these devices were at least the size of a desktop (TV, stereo receiver) and often were the size of an entire room or building (computer). In such devices, space for a keyboard or other conglomeration of keys, switches, etc, which allowed for user control of the device was not a concern, since the device itself was so large.
But technology marched on, and rapid advances were made in the miniaturization of the circuitry required to perform the functions of electronic devices. The vacuum tube gave way to the transistor. The transistor gave way to the integrated circuit. Today's VLSI (very large scale integration) circuits are capable of storing millions of transistors on a single chip. As the circuitry for electronic devices got smaller, the devices themselves got smaller. An electronic device that used to take up a whole room can now literally fit in the palm of a user's hand, or on their wrist.
While the ongoing miniaturization of electronic devices has truly been a revolution in technological progress, it has not been without its problems. One such problem is that the space for a keyboard or other conglomeration of keys, switches, etc, which allowed for user control of the device is now often the critical path that dictates the size of an electronic device. Everything from computers to watches could be made smaller and more efficient if space for user control of the device could be minimized